This invention relates to rubber articles having improved slip coatings and to methods of providing same. More particularly, the invention relates to rubber articles, such as sterile surgeon's gloves, which are provided with an improved slip coating. Still more particularly, the invention relates to such articles and methods wherein the slip coating is an essentially rubber-free synthetic resin layer.
It has previously been proposed to provide slip finishes on rubber articles such as rubber gloves or girdles by various methods. For example, the surface of a rubber glove can be halogenated with bromine or chlorine to make it slippery. However, this treatment may result in very poor aging properties. Discloration can begin almost immediately and, within a month, the halogenated surface may become hard and brittle and brown in color. This can be avoided only by taking great care in the halogenation process and even then there is no assurance of obtaining a uniform, sustained, slip film. Waxes and silicones have been used but these provide only a temporary solution as these materials rub off in a very short time. It has further been proposed in U.S. Pat. No. 3,286,011 issued Mar. 18, 1964, and U.S. Pat. No. 3,411,982 issued Mar. 18, 1964, to provide a slip finish comprising a rubber latex and a resin latex. While such coatings reduce the coefficient of friction of the rubber article to a slight extent, it is desirable to further reduce the coefficient of friction. For example, it is desirable to further reduce the coefficient of friction to make it easier to put on and take off a rubber article such as a rubber glove.
In our co-pending application Ser. No. 220,692, we have disclosed an excellent resin slip finish for rubber articles. The resin used is a vinyl chloride-alkyl acrylate copolymer or a vinylidene chloride-alkyl acrylate copolymer. While the slip finish is excellent, it may produce a "cobblestoning" effect when the rubber article is stretched to a large extent, of for example, over 450 percent. In surgeon's gloves, for example, stretchability of 700 percent is desired. Where gloves in accordance with our earlier invention are stretched to that extent, they tend to cobblestone, a condition which is not desirable in use.
It is an object of the present invention to provide an improved slip coating on a rubber article. It is a further object of the invention to provide improved methods of providing slip coatings on rubber articles. It is still a further object to provide a rubber article having a slip coating which substantially reduces the coefficient of friction of the rubber surface on which the coating is applied, and which can be stretched a very large amount without adverse effect.